: I just learned that mercury is in fact the closest planet to the earth. What is this madness and since when?

Question

: I just learned that mercury is in fact the closest planet to the earth. What is this madness and since when?

In: 3690

Answer 1

It’s not the closest planet to earth. It’s *most often* the closest planet to earth.

All planets revolve around the sun:

> (S) . . M . . V . . E . . M . . J . . S . . U . . N . . P

But they are practically never in a neat line up like this. Some are on the other side, some are “up” or “down” or somewhere in between.

So let’s look at the other extreme (for earth):

> E . . _ . . _ . . (S) . . M . . V . . _ . . M . . J . . S . . U . . N . . P

So seen from Earth:

* Mercury is anywhere between 2 planets away up to 4 planets away
* Venus is anywhere from 1 planet to 5 planets away
* Mars is anywhere from 1 planet to 7 planets away
* Jupiter is anywhere from 2 planets to 8 planets away
* etc.

*this is a* ***huge*** *simplification. The distances between the planet’s orbits are very different and not regular but for the explanation it doesn’t matter.*

So while Venus and Mars *can* be closer to Earth than Mercury, they can also be *much further* away than Mercury. This works out that most of the time Mercury is closer to Earth than Mars or Venus.

Funnily enough this is true for all other planets as well. Mercury is also usually the closest planet to Venus, Mars, … even Neptun or Pluto.